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Fromherz, T.; Koppensteiner, E.; Helm, M.; Bauer, G.; Nützel, J. F.; Abstreiter, G.

doi:10.1103/physrevb.50.15073

Cited by 100 publications

(62 citation statements)

References 37 publications

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“…kÁp method tools are more practical as they can be used on desktop or laptop computers and do not require access to significant computational resource. For intersubband absorption in SiGe QWs, a range of 6-band kÁp tools have demonstrated good agreement with experimental results in both the mid-infrared [19][20][21] and the far-infrared (THz) regimes. 18,[22][23][24] Key to this accuracy are the input parameters and also the level of bowing of many of the parameters for compositional changes as simple linear extrapolations between the Si and Ge parameters do not always provide accurate modelling.…”

Section: Introductionsupporting

confidence: 62%

8-band k·p modelling of mid-infrared intersubband absorption in Ge quantum wells

Paul

2016

Journal of Applied Physics

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The 8-band k·p parameters which include the direct band coupling between the conduction and the valence bands are derived and used to model optical intersubband transitions in Ge quantum well heterostructure material grown on Si substrates. Whilst for Si rich quantum wells the coupling between the conduction bands and valence bands is not important for accurate modelling, the present work demonstrates that the inclusion of such coupling is essential to accurately determine intersubband transitions between hole states in Ge and Ge-rich Si1−xGex quantum wells. This is due to the direct bandgap being far smaller in energy in Ge compared to Si. Compositional bowing parameters for a range of the key modelling input parameters required for Ge/SiGe heterostructures, including the Kane matrix elements, the effective mass of the Γ2′ conduction band, and the Dresselhaus parameters for both 6- and 8-band k·p modelling, have been determined. These have been used to understand valence band intersubband transitions in a range of Ge quantum well intersubband photodetector devices in the mid-infrared wavelength range.

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Section: Introductionsupporting

confidence: 62%

8-band k·p modelling of mid-infrared intersubband absorption in Ge quantum wells

Paul

2016

Journal of Applied Physics

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“…The use of a virtual substrate, which is a thick buffer layer on graded SiGe, results in a different inplane lattice constant of the add-on layer due to relaxation. Virtual substrates change the strain configuration in Ge QDs (Fromherz et al, 1994). The Ge 1-x Si x / Si interface layer may become partly strain-free alloy.…”

Section: Strain Induced Separation Of Confined Chargesmentioning

confidence: 99%

Quantum Mechanics Design of Two Photon Processes Based Solar Cells

Karoui¹,

Kechiantz²

2012

Some Applications of Quantum Mechanics

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“…Up to now most of the work has been concentrated on n-doped GaAs QWIPs where the superior transport of the photoexcited electrons above the barriers results in detectivities as high as D * λ ≥ 10 11 cm √ Hz W −1 . For this purpose optical couplers like gratings [3] or random scatterers [1] have been employed, which provide a component of the electric field parallel to the growth direction necessary for intersubband absorption in n-doped quantum wells due to the symmetry of the conduction band at the -point.In p-doped QW the restriction introduced by the quantum mechanical selection rule is removed due to the coupling of heavy-hole, light-hole and spin-orbit split-off subbands [4][5][6][7]. The desirable normal-incidence detection without optical couplers has been demonstrated in p-type GaAs [8] as well as p-type SiGe QWIPs [4,6].…”

mentioning

confidence: 99%

“…In p-doped QW the restriction introduced by the quantum mechanical selection rule is removed due to the coupling of heavy-hole, light-hole and spin-orbit split-off subbands [4][5][6][7]. The desirable normal-incidence detection without optical couplers has been demonstrated in p-type GaAs [8] as well as p-type SiGe QWIPs [4,6].…”

mentioning

confidence: 99%

“…In this letter we report the results of our experimental and theoretical work on a bound-to-continuum Si 0.64 Ge 0.36 /Si QWIP operating between 3 and 8 µm. The investigations were restricted to moderately doped structures where free-carrier and many-body effects do not complicate the understanding of the relation between intersubband absorption and photoconductivity [5,7]. The detector samples investigated in this work were grown on a (001) Si substrate (ρ ∼ 1500 cm) by molecular beam epitaxy.…”

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confidence: 99%

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Polarization-dependent intersubband absorption and normal-incidence infrared detection in p-type Si/SiGe quantum wells

Kruck

Weichselbaum

Helm

et al. 1998

Superlattices and Microstructures

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A detailed study of the polarization dependence of subband absorption and photoconductivity in pseudomorphic p-type Si/Si 0.64 Ge 0.36 quantum wells is presented. The fabricated quantum well infrared photodetectors (QWIP) show a photoresponse between 3 and 8 µm with a peak-wavelength of λ p = 5 µm under normal incidence illumination. At the optimum bias operating point a detectivity D * λ = 2 × 10 10 cm √ Hz W −1 is achieved. On the basis of a self-consistent six-band Luttinger-Kohn calculation the p-and s-polarized intersubband transitions, leading to the observed photoconductivity, are identified. c 1998 Academic Press Limited Key words: Si/SiGe, intersubband absorption, infrared detector.Optical transitions between confined subbands in doped quantum wells have attracted much interest because they allow the realization of sensitive infrared detectors for the spectral range between 3 and 20 µm [1,2]. The high quantum efficiency and uniformity of the so-called quantum well infrared photodetectors (QWIP) makes them especially attractive for thermal imaging applications. Up to now most of the work has been concentrated on n-doped GaAs QWIPs where the superior transport of the photoexcited electrons above the barriers results in detectivities as high as D * λ ≥ 10 11 cm √ Hz W −1 . For this purpose optical couplers like gratings [3] or random scatterers [1] have been employed, which provide a component of the electric field parallel to the growth direction necessary for intersubband absorption in n-doped quantum wells due to the symmetry of the conduction band at the -point.In p-doped QW the restriction introduced by the quantum mechanical selection rule is removed due to the coupling of heavy-hole, light-hole and spin-orbit split-off subbands [4][5][6][7]. The desirable normal-incidence detection without optical couplers has been demonstrated in p-type GaAs [8] as well as p-type SiGe QWIPs [4,6]. A Si-based QWIP offers the additional advantage of having the same thermal expansion coefficient as the Si readout electronics, an aspect which is essential for the realization of large detector arrays operating under low temperature conditions (T ≈ 80 K). Also a direct monolithic integration with MOS readout circuitry is possible [9]. Another promising detector concept with considerable quantum efficiencies, which should be mentioned in this context, is the single heterojunction SiGe/Si device, where the free-carrier absorption

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Hole energy levels and intersubband absorption in modulation-doped Si/Si1−xGe<

Cited by 100 publications

References 37 publications

8-band k·p modelling of mid-infrared intersubband absorption in Ge quantum wells

8-band k·p modelling of mid-infrared intersubband absorption in Ge quantum wells

Quantum Mechanics Design of Two Photon Processes Based Solar Cells

Polarization-dependent intersubband absorption and normal-incidence infrared detection in p-type Si/SiGe quantum wells

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